One can use the novel as a topic starter for a discussion on
exoplanetary systems' architecture as well. If we set aside
the Solar system (keeping in mind the argument about the status
of PlutoA non-fictional account of the Pluto debate
can be found in How I Killed Pluto and Why It Had It
Coming, by Michael E. Brown, 2010. and about the hypothetical
Planet IX – see [1]}, [2]}),
then the
richest planetary system we know of is Kepler-90, with eight
planets [3]}. Incidentally, Kepler-90 is
a G type solar analog, but the majority of richest planetary
systems are found around M stars, just like Proxima. An example
of that is the seven-planet TRAPPIST-1
[4]}.
This apparent preference for late type host stars reflects the
observational fact that low mass stars tend to be orbited by
more, but lower mass planets, in comparison with Solar type
stars [5]}, although some planets may
have evaded detection [6]}. Indeed,
[7]} noticed some time ago that hot
Jupiters are rarely found around cool low-mass stars. Later
on this was explained with the limitations of the planet
formation in the protoplanetary disks – it is easy to
understand this intuitively: the lower the stellar mass, the
lower the mass of the protoplanetary disk, the lower the mass
of the planets that can form inside them. The effect is
boosted by an additional bias that the lower mass planets
are easier to discover around lower mass stars, than around
higher mass stars
[8]}, [9]}.
